A conventional shift control device for an automatic transmission for a vehicle includes an automatic shift mode for performing a shift operation by determining a shift stage or a gear ratio to be set on the basis of a running condition and a manual shift mode for performing a shift operation instructed by a manual operation of a driver. Such automatic transmission is configured, for example, to instruct an upshift or a downshift stage by stage by operating a gear shift lever in a manual range, or instruct an upshift or a downshift stage by stage every time a paddle, provided to a steering wheel, is pushed, thereby allowing to instruct a shift operation by a manual operation (see Patent Document 1 below for example).
As described above, in the manual shift mode of the conventional automatic transmission, the downshift operation can be performed by instructing a downshift by one shift stage per operation. Due to this, when a multistage downshift is desired, the downshift operation needs to be performed multiple times, taking much time for performing the multistage downshift. Since a downshift by the manual operation requires approximately 500 milliseconds to one second per operation, it takes approximately at least two seconds if a downshift, for example, by four shift stages is desired.
Automatic transmissions in recent years are significantly multistaged with small gear ratios, an engine braking may be insufficiently effective by downshifting only by one stage per operation. Due to this, at the time of applying an engine brake by a manually-operated downshift operation, multiple downshifts are required before resulting in an intended amount of engine brake and accordingly likely to need much time. Therefore, for example, when a user is about to apply an engine brake in response to a following distance closer to a front vehicle, the driver might carelessly approach the front vehicle, failing to keep a proper following distance. Thus, the manually-operated engine brake has been less user-friendly.
As a prior art for keeping the following distance to the front vehicle, for example, Patent Document 2 discloses vehicle speed control using a radar installation for acquiring information such as a relative position and a relative distance to the front vehicle so that based on such information, the driver can follow the front vehicle, keeping the following distance constant.
In addition, Patent Document 3, for example, discloses collision reducing brake control for evading or reducing collision by automatically apply a brake when an external sensor such as a camera or a radar installation detects an object in front of a vehicle.